package com.itheima.domain;

public class DemoHello {

    public static void main(String[] args) {
        Hello.i = 20;
        System.out.println(Hello.i);
        Hello hello = new Hello();
        Hello.i = 30;
        System.out.println(Hello.i);
      //sing();
    }


    public  void sing() {//所有的成员方法内部自带 this
        System.out.println("sing");
    }
}
